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Biomedical subjects

A Renard

Publications and source records attributed to A Renard.

At least 19 recordsLinked to original sources
PubMed2004

Effect of maternal low-protein diet and taurine on the vulnerability of adult Wistar rat islets to cytokines.

AIMS/HYPOTHESIS: A maternal low-protein diet has been shown to induce an increased susceptibility of fetal islets to cytokines, but this effect can be avoided by maternal taurine supplementation. Here, we question whether these effects persist until adulthood in the offspring, despite the animal having a normal diet after weaning. METHODS: Pregnant Wistar rats received a diet of either 20% or 8% protein (control [C group] and recuperated [R group] respectively), which was or was not supplemented with taurine (control treated with taurine [CT group] and recuperated treated with taurine [RT group] respectively) during gestation and lactation. When the female offspring reached adulthood, an OGTT was performed. In a second stage, islets were isolated from these offspring, then pretreated or not with taurine, and subsequently treated with cytokines. RESULTS: Fasting glycaemia was higher (p<0.05) and insulinaemia was lower (p<0.01) in the R group than in the C group. Taurine supplementation decreased insulinaemia in the CT group and tended to increase it in the RT group. After the OGTT, glycaemia in R animals was not different from that in the C group, despite a blunted insulin response (p<0.05) which was restored by taurine. Supplementation in C-group mothers led to a weak glucose intolerance. In vitro, more apoptotic cells were observed in R islets after cytokines treatment (p<0.01). The addition of taurine to the culture medium in the R and C groups protected the islets from the cytokines (p<0.01). Maternal taurine supplementation decreased the sensitivity of islets in the RT group (p<0.01), but increased sensitivity in the CT group (p<0.01). CONCLUSIONS/INTERPRETATION: The increased vulnerability of islets to cytokines due to a restriction of protein during fetal development was still evident when the offspring reached adulthood. The low-protein diet also induced hyperglycaemia in the presence of lower insulinaemia. Taurine supplementation protected adult islets of the R group from cytokine toxicity and restored the insulinaemia. However, unnecessary supplementation of taurine could have detrimental effects.

Animals↗
PubMed2004

[Glaucoma screening in Martinique. Results in 813 hospital employees].

INTRODUCTION: Several US and Jamaican studies have shown that glaucoma is more severe in black populations than in Caucasian populations, which would lead to the assumption that the people of Martinique have a high glaucoma risk. METHODS: A prospective study was conducted in workers of Fort de France University Hospital with the occupational medicine unit. Intraocular pressure was measured with a pulse air tonometer (Topcon CT 60) and visual field abnormalities were detected with automated perimetry using Humphrey frequency doubling technology (FDT). Patients with known glaucoma or with intraocular pressure over 21 mmHg and/or a visual field abnormality were referred to ophthalmology examination to diagnose ocular hypertension, open-angle glaucoma or normal-pressure glaucoma. RESULTS: The occupational medicine unit examined 813 workers. The sex ratio was 0.36, mean age was 45.35+/-8.4 years (22-64 years), and mean ocular pressure was 12.1+/-2.62 mmHg (6-28 mmHg). Roughly 20% of workers had a family history of glaucoma. We found 22 patients with glaucoma (2.7%) (CI95: 1.6%-4%): 12 patients had open-angle glaucoma (1.5%) and 10 patients were diagnosed with normal-pressure glaucoma (1.3%). Glaucoma prevalence increased with age, reaching 8% in patients over 55 years of age. Of patients with normal-pressure glaucoma, 42.9% had a family history of glaucoma. CONCLUSION: Our results confirm previous data from the literature that found higher glaucoma prevalence in black people and in particular in the mixed-race population of Martinique. In addition to this ethnic feature, the insularity of Martinique could support glaucoma expression. Easy and fast to use, FDT associated with the pulse air tonometer provides early detection of glaucoma.

Adult↗
PubMed2001

A human immunodeficiency virus Env inducible transcription system to examine consequences of gp120 expression.

According to several studies, the HIV-1 envelope gp120 protein and the co-receptor CXCR4 play an essential role in HIV-1 induced cell toxicity. Characterisation of the CD4-independent m7NDK isolate provided the opportunity of studying the effects of direct interactions between m7NDK gp120 and CXCR4. Therefore, an inducible expression system was designed enabling synthesis of HIV-1 Env proteins upon doxycycline induction. Analysis of the expression of the env gene of the m7NDK HIV-1 isolate revealed, unexpectedly, that even long-term expression of m7NDK gp120 did not result in cytotoxycity in CXCR4-positive or -negative cell lines. This is the first report of a CD4-independent HIV-1-protein inducible expression regulated through the Tet-On system and by an alternative splicing. Env inducible expression cell lines could constitute a useful cellular tool to undertake analysis of HIV Env protein expression.

Astrocytes↗
PubMed2001

[Role of radiotherapy in the treatment of cerebral meningiomas].

Cerebral meningiomas account for 15-20% of all cerebral tumours. Although seldom malignant, they frequently recur in spite of complete surgery, which remains the cornerstone of the treatment. In order to decrease the probability of local recurrence, radiotherapy has often been recommended in atypical or malignant meningioma as well as in benign meningioma which was incompletely resected. However, this treatment never was the subject of prospective studies, randomized or not. The purpose of this review of the literature was to give a progress report on the results of different published series in the field of methodology as well as in the techniques of radiotherapy. Proposals for a therapeutic choice are made according to this analysis. For grade I or grade II-III meningiomas, limits of gross tumor volume (GTV) include the tumour in place or the residual tumour after surgery; clinical target volume (CTV) limits include gross tumour volume before surgery with a GTV-CTV distance of 1 and 2 cm respectively. Delivered doses are 55 Gy into CTV and 55-60 Gy and 70 Gy into GTV for grade I and grade II-III meningiomas respectively.

Algorithms↗
PubMed2000

[Radiotherapy of brain astrocytomas and oligodendrogliomas of the adult].

Gliomas are moderately radiosensitive. The main prognostic factors are the anatomicopathological type and grade of glioma, the performance status, age of the patient and the extent of the surgery. According to data from the literature, high-grade gliomas should be given 60 Gy in five weekly fractions of 1.7 to 2 Gy in a volume including tumor or tumor bed, edema and a 2- to 3-cm margin. A dose of 45 Gy would be sufficient for low-grade gliomas, according to the results of a recent randomized EORTC trial. Brachytherapy and radiosurgery techniques may be indicated in selected cases.

Adult↗
PubMed1999

Determination of neutron spectra in a MOX plant for the qualification of the BD-PND bubble detector.

As a result of the introduction of the ICRP 60 recommendations and the increasing contribution of the neutron dose to the total dose of the personnel at the Belgonucleaire Mox fuel fabrication plant, the BD-PND bubble detector manufactured by Bubble Technology industries was introduced as a new, reliable personal neutron dosimeter. In the framework of the evaluation program of the bubble detector, measurements and calculations of the neutron spectra in the installations of the fuel fabrication plant were performed. The measurements were carried out with a ROSPEC neutron spectrometer, and the calculations were performed by means of the Monte Carlo code MCNP 4A. Comparison between measurements and calculations revealed good agreement. On the basis of the obtained neutron spectra, a correction factor was determined to take into account the new ICRP 60 recommendations and the difference between the calibration spectrum of the bubble detectors and the observed neutron spectra at the plant. This correction factor was applied to the calibration factor provided by Bubble Technology Industries.

Calibration↗
PubMed1998

Simultaneous determination of the lactone and carboxylate forms of the camptothecin derivative CPT-11 and its metabolite SN-38 in plasma by high-performance liquid chromatography.

CPT-11 (irinotecan) and mainly its metabolite SN-38 are potent antitumor derivatives of camptothecin. As the active lactone forms of both CPT-11 and SN-38 exist in pH-dependent equilibrium with their respective less potent open-ring hydroxy acid species, the simultaneous monitoring of both forms of both compounds is relevant. CPT-11 and SN-38 derivatives have quite different fluorescence responses. In order to avoid any compromise on the wavelength setting, we developed chromatographic conditions allowing simple automated wavelength setting changes which have been prevented using existing methods involving conventional C18 columns. This was achieved by means of a Symmetry C18 column combined to a gradient elution program using acetonitrile and 75 mM ammonium acetate plus 7.5 mM tetrabutylammonium bromide at pH 6.4. The developed conditions allowed an elution order suitable for a simple automated wavelength change in respect to reliable peak integration. CPT-11 and SN-38 derivatives were detected at lambda ex=362 nm/lambda em=425 nm and lambda ex=375 nm/lambda em =560 nm, respectively. The developed method allowed the detection of amounts less than 3 pg of each derivative injected on column. The method was successfully applied to pharmacokinetic and toxicokinetic studies in rat and dog.

Animals↗
PubMed1998

[Infiltrating carcinoma of the uterine cervix: epidemiology, prognostic factors, therapeutic strategies].

In industrialized countries cervical cancer has decreased over the past decades. This, thanks to wide spread screening campaigns of precancerous lesions and microinvasive diseases through regular pap smears starting from the beginning of sexual activity. The diagnostic is realized earlier, thus increasing the rate of curability. Unfortunately, the absence of such programs in underdeveloped countries has made cervical cancer the second cause of death by cancer among the world female population. This general review treats in a non exhaustive manner epidemiology and prognostic factors and secondly exposes the therapeutic methods that has become available in recent years.

Female↗
PubMed1996

Origin of aspartate-induced responses in rat cerebellar Purkinje cells.

The effects of glutamate, aspartate and N-methyl-D-aspartate (NMDA) on Purkinje cells and interneurons were investigated in cerebellar slice cultures using the whole-cell configuration of the patch-clamp technique. L-Glutamate and L-aspartate induced inward currents in Purkinje cells voltage-clamped at -60 mV. In standard external solution, the amplitude of the responses induced by the two amino-acids was a linear function of the membrane potential. L-Aspartate-induced currents were inhibited by 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX), a selective antagonist of non-NMDA receptors. NMDA, a selective agonist of NMDA receptors, had no effect of its own on the excitability of Purkinje cells, but was effective in blocking the responses induced by aspartate in Purkinje cells in a voltage-independent manner. In contrast, D-(-)-2-amino-5-phosphonovaleric acid (D-APV), a selective antagonist of NMDA receptors, had no effect on aspartate-induced responses. D-Aspartate also induced responses in Purkinje cells, and the amplitude of these responses was a linear function of the membrane potential. Currents induced by L- and D-aspartate were inhibited by dihydrokainate, a glutamate uptake blocker. In sodium-free external solution, glutamate still induced outward currents in Purkinje cells, whereas L- and D-aspartate no longer evoked any current. When sodium was replaced by lithium in the external medium, no change in the holding current could be detected in Purkinje cells maintained at -60 mV; moreover, in this bathing medium L-aspartate no longer evoked any current whereas glutamate-induced responses were still present. In contrast, interneurons were sensitive to both NMDA and aspartate applications, and these responses were antagonized by D-APV. In addition, aspartate still induced an outward current in sodium-free external solution. This study presents rather direct evidence in favour of L-aspartate as being a very selective NMDA receptor agonist in the cerebellum. L-Aspartate-induced currents in Purkinje cells are not due to activation of mixed NMDA/non-NMDA receptors, but are probably due to the release of L-glutamate induced by aspartate through glutamate uptake.

Animals↗
PubMed1995

Evidence for two types of non-NMDA receptors in rat cerebellar Purkinje cells maintained in slice cultures.

Pharmacological properties of non-NMDA receptors were investigated in Purkinje cells grown in rat cerebellar slice cultures and recorded in the whole-cell configuration of the patch-clamp technique. Dose-response curves for AMPA and domoate suggest that AMPA, in the concentration range tested, activated only AMPA receptors whereas, domoate activated two types of receptors, probably AMPA and kainate receptors, with EC50 values of 8 and 0.5 microM, respectively. The Scatchard analysis of the dose-response relationship for domoate also suggest that both kainate and AMPA receptors were activated by domoate with approximate affinities of 5 and 0.07 microM-1, respectively. The non-competitive non-NMDA receptors antagonist, GYKI 52466, reduced the amplitude of both AMPA- and domoate-activated currents, with a greater potency in reducing currents evoked by AMPA (IC50 = 10 microM) than those induced by domoate (IC50 = 105 microM). These results suggest that, in addition to AMPA receptors, Purkinje cells express kainate receptors and that these two types of non-NMDA receptors can be distinguished from each other on the basis of several pharmacological properties, including affinity for AMPA, domoate and GYKI 52466.

Animals↗
PubMed1993

Expression of the bovine viral diarrhoea virus Osloss p80 protein: its use as ELISA antigen for cattle serum antibody detection.

The putative gene encoding the cytopathic bovine viral diarrhoea virus (BVDV) Osloss strain p80 protein was amplified by PCR and inserted into a T7 promoter-based vector for expression in Escherichia coli. Bacterial expression led to cytoplasmic insoluble inclusion bodies which were denatured by urea treatment and renatured by dialysis. Rabbit antisera were raised against this p80 recombinant antigen and assayed for the immunoprecipitation of either p120 or p80 protein from cytopathic or non-cytopathic BVDV biotype-infected bovine cells. The p80 gene sequence was also integrated into a baculovirus genome for its expression in Spodoptera frugiperda insect cells. The recombinant proteins isolated from bacteria or insect cells showed distinct antigenic properties when analysed by ELISA. Their ability to detect anti-BVDV specific antibodies was examined in a monoclonal antibody-based competitive ELISA performed on a series of field cattle sera. This comparative assay revealed the superiority of the insect cell-mediated expression to mimic the natural BVDV antigen produced by cell culture. The baculovirus/insect cell recombinant antigen gave the highest correlation between the ELISA-detected antibodies and the corresponding virus neutralization data.

Animals↗
PubMed1993

Five hours to identify immunotolerant cattle, persistently infected with bovine virus diarrhoea virus.

Detection of animals which are persistently-infected with bovine virus diarrhoea virus (BVDV) is of prime importance in the control of pestivirus infections in cattle, as these animals constitute the main reservoir of the virus. Identification of such animals can be readily performed using crude whole blood samples with a sandwich enzyme-linked immunosorbent assay (ELISA) requiring only approximately five hours. This ELISA uses a combination of monoclonal antibodies as the capture agent and an immunological amplification step of the specific signal for detecting the non-structural 80/120 kDa protein of BVDV. The degree of correlation between this ELISA and virus isolation as the reference method is 100% for animals older than six months.

Animals↗
PubMed1992

Stabilization of T7-promoter-based pARHS expression vectors using the parB locus.

We describe a modification of the pAR3040 vector which results in its efficient stabilization during cell division. The parB locus of the plasmid R1 was introduced into the plasmid, pAR3040, to construct the pARHS vectors. These vectors are stable for at least 60 cell generations, even in the absence of selection by an antibiotic present in the culture media, both with or without IPTG induction.

Base Sequence↗
PubMed1991

Sequence of a cDNA carrying the glycoprotein gene and part of the matrix protein M2 gene of viral haemorrhagic scepticaemia virus, a fish rhabdovirus.

A cDNA clone encoding for the glycoprotein of the viral haemorrhagic scepticaemia virus, a fish rhabdovirus, has been sequenced. The cDNA was 2035 bp long and contained two open reading frames (ORF). A 1523 bp ORF corresponded to the glycoprotein and was adjacent, on its 5' side, to an incomplete 372 bp ORF. Although the protein encoded by this ORF displayed no similarity with other rhabdovirus proteins, it was supposed that the cDNA had been reverse-transcribed from a readthrough mRNA encoding successively for the M2 and the G proteins.

Amino Acid Sequence↗
PubMed1991

Identification and production of pestivirus proteins for diagnostic and vaccination purposes.

Using a panel of monoclonal antibodies (MAbs) previously characterized by seroneutralization, immunofluorescence and radioimmunoprecipitation, we have identified Pestivirus proteins useful for diagnostic purposes from the cytopathic Osloss isolate of bovine viral diarrhea virus (BVDV). Proteins that should be useful for vaccination have also been analysed. Cell-free translation of RNA from glycoprotein-coding cDNA fragments produced, when synthesized in the presence of canine pancreatic microsomes, two glycosylated proteins that were independently recognized and immunoprecipitated by two distinct classes of neutralizing MAbs. A similar in vitro procedure was carried out on nonstructural protein-coding sequences and allowed to identify a viral translation product that specifically reacted with MAbs directed against the 80 kDA protein of a number of Pestivirus strains. Its positioning within the polyprotein encoded by the viral genome was refined by epitope scanning using synthetic hexameric peptides. This viral antigen was further expressed in E. coli, produced as inclusion bodies and used successfully as an ELISA antigen in both competitive and indirect assays for the detection of BVD antibodies in cattle sera.

Animals↗